A session identifier may include information that identifies a session (e.g., a semi-permanent interactive information interchange) between a user device and a server device (e.g., a server device that hosts a web site). The server device may generate the session identifier when the user device sends an initial request to the server device, and may provide the session identifier (e.g., in a session cookie) to the user device. The user device may provide the session identifier to the server device each time the user device sends a request to the server device) such that the server device can identify the session with the user device.